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    Type:Task 
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    Resolution: Duplicate
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    Priority:Major - P3 
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    None
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    Affects Version/s: None
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    Component/s: mongostat
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    None
It would be far easier to predict replication lag and the rate at which replication lag was increasing with a few new fields in the output of mongostat.
Fields such as the following would be very useful:
- The rate of generation of op-log records on the master (in records/sec)
- The rate of processing of op-log records on the slaves (in records/sec)